For Visa, Mastercard and Discover CardsTurn the card over and look at the signature box. Printed in the signature box is either the entire 16-digit credit card number or just its last 4 digits. The 3-digit security code follows. On new Visa cards, the code is embedded nearby in plastic.

For American Express CardsThe security code is always located above the account number on the face of the card, sometimes on the left side and sometimes on the right. (Note: Some American Express cards have a 4-digit number below the account number. This is not the security code CSC.)